Beam antenna system



1948. c. L. ROUAULT.

BEAM ANTENNA SYSTEM Filed April 19, 1945 Pig].

sol/Pa; OF I SIGNHL [Ms-ear 28 I F0 7/4 77/VG JO/IVT' Fig.2.

Inventor: Charles L. Rouault His Attorney.

Patented Aug. 3, 1948 UNITED STATES NT ()FFICE BEAM ANTENNA SYSTEM Gharles L. Renault, Schenectady, N. 11, assignor to General Electric Company, a corporation of New York 6 Claims.

This invention relates to antenna systems and more particularly to antenna systems adapted for radiating sharply directive beams of radio frequency energy.

Systems have been proposed in which periodic pulses of short wave oscillations have been radiated into space and an echo of each pulse has been received in the period prior to the next succeeding pulse. In communication systems of this type, there have been provided antenna systems from which are radiated periodic pulses and by which the echoes are intercepted. Antenna systems for such purposes are usually of a type projecting a sharp beam of radio energy into space and are usually provided with a reflector which may be of any suitable surface of revolution but are most commonly of paraboloid form. The

beam is projected at a small angle to the axis of the reflector and the radiator is located at substantially the focal point on the axis of the reflector in order to rotate the beam about the sur face of a cone, the axis of which is the axis of the reflector. The radiating system including the reflector is arranged to be oriented both in elevation and in azimuth by suitable mechanical means so that the axis of the paraboloid can be directed at a remote object such as a target and maintained so oriented.

Such systems have been generally described and claimed in application, Serial No. 482,403, to Donald E. Norgaard, filed April 9, 1943, and application, Serial No. 414,126, of Sidney Godet, filed October 8, 1942, now Patent No. 2,412,612, granted December 17, 1946, both of which applications are assigned to the same assignee as the present invention.

It is an object of my invention to provide a new and improved antenna system for such systems of communication.

It is another object of my invention to provide a search antenna for such a system which is simple in form, easy of manufacture and assembly, relatively inexpensive, and so arranged that the radiating parts are not subject to any appreciable centrifugal force.

The features of my invention which I believe to be novel are set forth with particularity in the appended claims. My invention itself, both as to its organization and manner of operation, together with further objects and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. 1 is a sectional side elevational view of apparatus embodying the principles of my invention, and Fig. 2 is 2 an enlarged view of the antenna element and associated reflector element shown in Fig. 1.

In the accompanying drawing, there is shown an antenna system comprising a para-boloid re- 'fiector iii, an antenna member II and a reflector member l2. The antenna member II is of the dipole type including substantially colinear or axially aligned elements It and I l. The dipole is located at or near the focus of the paraboloid reflector and the axis of the reflector Ill passes through the dipole at or near the midpoint thereof. While there is illustrated a reflector element 92, it will be understood that the element 12 may be omitted, if desired. However, the reflector element i2 reflects energy radiated directly outward- 1y from the antenna element H into the paraboloid reflector ll) so that a sharper beam results when the reflector element I2 is used.

Means is provided for exciting the antenna element i I. This means comprises a source of signal energy which may be considered to be included in the box indicated by numeral 15, an open transmission line 16 and a concentric transmission line ill, the latter comprising an inner conductor 18, represented by the dotted lines in Fig. 1, and an outer cylindrical conductor or tube is through which the inner conductor extends. The inner conductor extends along the axis of the paraboloid.

The source of signal energy or transmitter contained within the box I5 produces pulses of oscillations of high frequency energy and supplies them to the transmission line I6. The pulses are transferred to the concentric transmission line section H through a suitable type of rotating joint, indicated by the numeral '20. The antenna array comprising the elements H and I! also receives echo pulses and supplies them to a suitable pulse receiver which may also be considered to be contained within the box I5.

Means is provided for shifting the antenna beam pattern from coincidence with the axis of the reflector and for rotating the antenna assembly so that a rotating beam is projected into space. In the illustrative form of my invention, the dipole is tilted, that is, disposed at an angle of other than with respect to the axis of the para-boloid reflector. This arrangement causes the projected beam to have an angle of a few degrees with respect to the paraboloid axis. The beam shift may be increased further by unbalancing the currents in the antenna elements 83 and Hi. It is well known that in order to have balanced current in the arms or elements of a dipole when those arms or elements are of equal radiated from the transmission line It to the antenna member ll consists only of the concentric transmission line H and the rotating joint 20.

Omission of the line balancing; cylinder thus causes further beam shift. If :still. additional beam shift is required the arms or elements 13 and M of the antenna member H may be made of different lengths, as shown in the drawing.

The above described antenna array is not my invention, but is described and claimed in copending application Serial Nopa85fifll of-B; P.Brown-,,

filed May 4, iii l3; and'assignedto the. same-as-- signee the present invention."

In order to permit the--detenmination ofythe;

elevation and azimuth .of-theobject from whichechoes are'reccived, it is desirable to rotatethe displaced pattern about theaxis-oi the'paraboloidreflector. For this purpose there -is provided .a'

su table motor 21 receivingelectrical energy from a suitable source, not showmandcarrled by the base plate Ssiattached to the parabcloid reflector in any suitable manner; The motor is operatively connectedto the outer'conductor: 19 through suitable gears 22 and 23 carried by the shaft of the motor-end the outer conductor-ortube l9 respectively; The rotation producingmeansand the transmission line H are mountedas shown center of the parabcloid reflector.

so of" the mechanical couple resulting the unbalanced disposition of the dipole P from there results a tendency of theparts- Of the antenna a embly to Whip during rotation. In order to iirnize the effects of centrifugal iorce, the tran. close as practicable to the dipole.v For thisrpllre .-ssionline section I? is supportedjas pose there has been provided-a conically shaped supporttli located atthe center-of the paraboloid:

reflector and attached to the base 36 at'the, large end, Suitable bearing means 25 is providedgat the small end of thecone. If'desired a bearing may also be provided Wheretransmissionline l! pa sses through the supporting structure. At any rate, the transmission line section-l1 is preferably 1 supported at two points; although some additional support is provided through the inter meshing gears. It will be noted further that theconical member 25 and thebaseplate 36-;serve as a housing for the gears.

In order to obtain intelligence which may be employed to cause theantenna system,-including the paraboloid reflector, to follow-the target-or source of echo, there hasbeen shown atWo-p'hase' alternator 28 suitably-carried by-the paraboloid,

reflector, as on the base plate 36-, and caused to rotate by means ofa suitable-gear 29 attached to the shaftof the alternator and meshing with the pinion or gear z's. The'output of the alternator is utilized to energize suitable elevation and azimuth controlling mechanism in the manner described in the above identified copending,appli.-. cations of Donald E. Norgaardiand Sidney Godot.-

As shown in Fig. 2, meansisprovidedfor connecting the elements it and [4 of therantenna."

member H to the transmissiondine members; l8? and:i 9. i'The shorter: membenl 4; may be connects;

4 ed directly to the outer conductor la in any desired fashion, as by welding, for example. Means is provided for passing the longer element i3 through the outer conductor i9 into engagement with the conductor 18 and for securing the element 13 to the outer conductor in such a manner as to lend support to the inner conductor and thereby minimize the effects of centrifugal force on the inner conductor and the reflecting member l2. The means connectin the elements 13 andlthe outer conductor ll], of course, is electrically insulative. In the form of my invention illustrated herein, this purpose is accomplished by providing a stud 39 having a threaded laterally extending portionv 3! adapted to engage the threads of a suitably tapped bore in the end of the arm l3. An insulating member 32 is retained within or adjacent to an opening 31 in the outer member 19 between the stud 35 and end of the arm I3. For example, the edge of the member 32 may be encircled by a metal washer 32a and the ,outeredge of the member or washer 32a may be engaged by a flanged member 33 having inter nal threads engaging suitable threads in the outer.

surface of the washer, 32a. The inner. end of the stud so is securely fastened to the inner conduc tor it as bylmeans of a suitably threadediastene ing member a l .passing through a suitableopen ing-in the conductor it into suitable threaded engagementwith the bore in the stud as. Thearmi3 is shown bent at the inner end thereof in order to approach the inner conductor at right angles thereto for convenience of assembly. Withlthis arrangement, the stud maybe fastened in posi-' tion, the insulative washer applied over, the-' threaded endfil of the stud and the flanged member 33 fastened in place. The arm I3 may thenbe screwed onto the lateral portion 3! of the. stud. Therefiector-member 12 may be securedrto the" end of the inner conductor IS in any-suitable:

manner as :by means of the threaded fasteningmember35. With this; arrangement the innerconductor is-maintained in coaxial alignment."

with the outer conductor during'rotation lot the antenna system.

The mechanical details of the system described above provide-an arrangementeasy of assembly or disassembly. As shown in Fig. 2, the outer end. of theouter conductor 19 is out 01f at a substantial angle to its axis (greater than the angle of the dipole to the axis of conductor I9) and the dipole arm-I l is connected-to conductor l9 adiacent the shorter portion or-side thereof. The opening 31 through which the arm it passes is in theJongenportion or side of conductor l9 and is in approximate alignment with the axis of arm itltsoathat arm 13 may engage inner conductor I 8 insubstantial alignment With arm M. above features result in ready accessto fastening means. without disassembly of the system.

While I have shown and described a particular embodiment of-my invention, it will be obvious;

to thoseskilled in the art that changes and'modifications may be made without departing from my invention in its broader aspects, and I, therefore,

aim in the appended claims to coverallsuch' changes and modifications as {all within the true spirit and, scope of my invention.

WhatIclaim as-new and desire to secure by Letters Patent of the United States is:

1. In anantenna assembly comprising a dipole having a pair of substantially axially aligned arms and a coaxial transmission line having inner and outer concentrically disposed conductors for energizing said dipole, one of said arms being secured The to the outer conductor of said line at the end thereof, means for securing the other of said arms to the inner conductor of said line near said end, means for rotating said transmission line at high speed, and supporting means for securing said other arm in fixed position with respect to said outer conductor, thereby to support said inner conductor in substantially coaxial alignment with said outer conductor against the effects of centrifugal force during said rotation at high speed.

2. In an antenna assembly comprising a dipole having a pair of substantially axially aligned arms and a coaxial transmission line having inner and outer concentrically arranged conductors for energizing said dipole, one of said arms being secured to the outer conductor of said line at the end thereof, means for securing the other of said arms to the inner conductor of said line near said end, means for rotating said transmission line at high speed, and an insulating member secured to said outer conductor, said other arm also being secured to said insulating member, said other arm being upported fixedly with respect to said outer conductor through said insulating member, whereby said inner conductor is maintained in substantially coaxial alignment .with said outer conductor against the efiect-s of centrifugal force during said rotation at high speed.

3. In an antenna assembly comprising a dipole having a pair of substantially axially aligned arms and a coaxial transmission line having inner and outer concentrically disposed conductors for energizing said dipole means for rotating said transmission line at high speed, one of said arms being secured to the outer conductor of said line at the end thereof, said outer conductor having .an opening therethrough and near the end thereof, and an insulating member secured at said opening, said insulating member having an opening therethrough which is smaller than the opening in said outer conductor and substantially coaxial therewith, a portion of said other arm passing through said opening in said insulating member and being secured to said inner conductor, said other arm also being secured to said insulating member and supported fixedly with respect to said outer conductor through said insulating member, whereby said inner conductor is maintained in coaxial alignment with respect to said outer conductor against the effects f centrifugal .force during said rotation at high speed.

4. In an antenna system comprising a dipole having a pair of substantially colinear arm and a coaxial transmission line having inner and outer concentrically disposed conductors for energizing said dipole means for rotating said transmission line at high speed, one arm of said dipole being fastened to the outer of said conductors .at the end thereof, said outer conductor having an opening therethrough diametrically opposite said one arm and in approximate alignment therewith, the other arm of said dipole having a portion extending through said opening into electrical connection with the inner .of said conductors, and insulating means arranged to locate positively said other arm and said outer conductor whereby said conductors are also located positively with respect to each other and relative motion therebetween, due to the efiec'ts of centrifugal force is minimized during said rotation at high speed.

5. In an antenna system comprising a dipole having a pair of substantially colinear arms and a coaxial transmission line having inner and outer concentrically disposed conductors for energizing said dipole, an end of said outer conductor being cut off at .a substantial angle to the axis thereof, one arm of said dipole being fastened to said outer conductor adjacent the shorter side thereof and at an angle to the axis of said conductors, the last mentioned angle being substantially less than the angle at which said outer conductor is out, said outer member having an opening therethrough in substantial alignment with the axis of said one arm, the other arm of said dipole having a portion extending through said opening into electrical engagement with said inner conductor and in substantial axial alignment with said one arm, fastening means for securing said other arm to said inner conductor in substantial alignment with said one arm and beyond the shorter side of said outer conductor whereby said fastening means is always accessible without disassembly of said system.

6. In an antenna system comprising a dipole having a pair of substantially colinear arms and a coaxial transmission line having inner and outer concentrically disposed conductors for energizing said dipole, an end of said outer conductor being cut .off at .a substantial angle to the axis thereof, one arm of said dipole being fastened to said outer conductor adjacent the shorter side thereof and at an angle to the axis of said conductors, the last mentioned angle being substantially less than the angle at which said outer conductor is cut, said outer member having an opening therethrough in substantial alignment with the axis of said one arm, the other arm of said dipole having a portion extending through said opening into electrical engagement with said inner conductor and in v substantial axial alignment with said one arm,

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,828,705 Kolster Oct. 20, 1931 2,083,242 Runge June 8, 1937 2,258,953 Higgins Oct. 14, 1941 2,298,449 Bailey Oct. 13, 1942 2,401,344 Espley June 4, 1946 

